The present invention relates to the processing of tariff data for a telecommunication connection. In particular, the invention concerns a new and Improved method and system for the transmission of charge data to a registering point.
A prior-art method for charging for a telecommunication connection is based on CHG messages (CHarGe message). CHG messages are used to transmit call tariff information, which is stored in charging records (CDR). This method is used e.g. in ISDN networks and it necessitates the use of ISUP2 signalling (ISUP2, ISDN user part, version 2). The charge message is a tariff message generated in the B-subscriber""s telephone exchange and transmitted to the registering point during call set-up. The registering point is often the A-subscriber""s telephone exchange. It may also be a telephone exchange between two networks or any ocher telephone exchange to which the subscribers are connected. In this context, A-subscriber means the committer of the connection, and B-subscriber means the subscriber with whom a connection is to be set up.
To verity that the charge data have been received at the registering point and that the registering point has approved them, an acknowledgement or CHGA (CHarGe Acknowledgement) message is sent to the network element which sent the charge message. If the network element which has sent a CHG message does not receive a CHGA message within a certain length of time, then the telecommunication connection is disconnected.
The charge data can be changed during the connection by sending a replacing charge message (replacing CHG tariff) to the registering point. This message transmitted to the registering point contains a new value and an indicator specifying the quantity to be replaced with the new value. The CHG messages are transmitted through all the telephone exchanges along the connection to the registering point, which stores them for use in calculation. A signalling point code included in the charge message is used in acknowledging the message to direct the acknowledgement to the exchange which sent the charge message. The signalling point code contains the addresses of the receiving network element and the network element which has sent the message. Moreover, charge messages contain an indication of the tariff category to be used, of which there is a limited number in use.
From the charge and call data accumulated at the registering point, a charging center later calculates the price to be charged to the subscriber.
In call set-up referred to above, problems are encountered in situations where charge messages of the same tariff category are sent from both the originating and terminating sides. In a call for which charge messages are generated on the originating and terminating sides of the same network element, the signalling point codes for the messages are the same. If the tariff categories of the messages are also the same, then the registering point is unable to distinguish the messages from each ocher and the call is disconnected.
The object of the present invention is to eliminate the drawbacks described above or at least to significantly alleviate them.
A specific object of the present invention is to disclose a new type of method and system for transmitting charge messages to a registering point an a situation where messages are sent from the originating and terminating sides of the called subscriber""s telephone exchange.
The present invention concerns a method for the processing of CHG messages (CHarGe messages) in a telecommunication system. This telecommunication system comprises a registering point where received charge messages are distinguished from each other e.g. on the basis of tariff category and signaling point code. Moreover, the system comprises a first telephone exchange, to which the A-subscriber is connected, and a second telephone exchange, to which the B-subscriber is connected. The second telephone exchange uses charge calculation based on charge messages of both the originating and terminating sides. In this charge calculation a charge message is sent from the originating side to the registering point during the establishment of the connection. In the method of the invention, a charge message received on the originating side from the terminating side is checked and the charge data for the originating and terminating sides are combined if they bear a similarity to each other. After this, according to the invention, the charge message is modified to form a replacing charge message containing the combined charge data, and the message is sent to the registering point.
In an embodiment of the method, the tariff data sent in the charge message from the originating side to the registering point and the tariff data sent in the charge message from the terminating side are added together if the tariff categories of these messages are the same. The sum is sent in the replacing charge message to the registering point.
In a preferred embodiment, an acknowledgement message is sent from the originating side to the terminating side after the registering point has acknowledged edged the replacing charge message sent from the originating side. This is done because the terminating side waits for an acknowledgement before continuing its functions in the normal manner.
According to the invention, all charge messages received by the originating side from the terminating side in which the charge data bear similarities to the charge data sent to the registering point can be combined. The registering point of the invention is preferably located in the first telephone exchange. The signalling used in the telecommunication network may be ISUP2 signalling (ISUP2, ISDN user part, version 2).
The invention also relates to a system for the processing of charge messages in a telecommunication system as described above. In the system of the invention, the originating side of the second telephone exchange comprises means for checking a charge message sent by the terminating side and means for combining the charge data sent by the originating side to the registering point and the charge data received from the terminating side if the charge data sent by the terminating side bear similarities to the charge data sent from the originating side to the registering point. Moreover, the system of the invention comprises means for modifying the charge data so as to form a replacing charge message containing combined charge data and means for sending a replacing charge message to the registering point.
In a preferred embodiment of the invention, the originating side of the second telephone exchange comprises means for summing the tariff data sent to the registering point and the tariff data received from the terminating side when the tariff categories in the charge messages are the same. Moreover, the originating side of the second telephone exchange preferably comprises means for generating an acknowledgement message and sending it to the terminating side after the registering point has acknowledged the replacing charge message sent to it.
In a preferred embodiment of the invention, the originating side of the second telephone exchange comprises means for combining all charge messages received from the terminating side if the charge data bear similarities to the charge data sent to the registering point.
The registering point of the invention is preferably located in the first telephone exchange. The signaling used in the telecommunication network may be ISUP2 signalling.
The invention helps achieve a successful telecommunication connection. It prevents the occurrence of error situations and call setdown if charge messages with the same tariff categories are sent from both the originating and terminating sides of a network element. The invention also allows the introduction of new services using originating and terminating side calculation.